Table 1.

Inclusion and exclusion criteria

Inclusion criteria
Diagnosis	1.) Non-specific CBP ≥ 45 days during the past three months, and
	2.) History of experienced psychological trauma*
Age	At least 18 years of age
Language	Fluent German language skills
Exclusion criteria
Pathology	- Specific pathologies of CBP (e.g., spinal canal stenosis, disc hernia, spondylolisthesis, infection, malignancy, Bechterew disease, and fracture)
	- Sciatica pain ≥ than back pain
	- Severe physical or psychiatric co-morbidity
	- Cognitive impairment
Pension status	Active or planned worker’s compensation, disability or personal injury claims
Medical status	Planned other or ongoing psychotherapy, change in medication in the last three months

*Psychological trauma will be assessed using the German Version of the Posttraumatic Diagnostic Scale (PDS-D)[46]. Patients who at least answer one trauma item positive will be classified as patients with experienced psychological trauma. All other patients will be classified as patients without psychological trauma. For details see[43].